Quick-coupling device for pipelines and the like

ABSTRACT

A quick-coupling device ( 1 ) for circuits for circulation of fluids under pressure comprising a socket ( 2 ) and a fitting element ( 3 ) that can be housed in the socket, the socket ( 2 ) including an outer body ( 5 ) defining at least part of a first channel ( 2   d ) and comprising an annular cavity ( 5   a ) opening on the first channel ( 2   d ), a substantially annular constraint element ( 4 ) at least partly housed in the annular cavity ( 5   a ) and movable therein, and including a plurality of constraint sectors ( 7 ) made up of circular sectors of the constraint element ( 4 ), adapted to be mutually moved in a radial direction and defining a release position at which the constraint element ( 4 ) is retracted into the annular cavity ( 5   a ) so as to enable movement of the fitting element ( 3 ) relative to the socket ( 2 ), and a tightening position at which the constraint element ( 4 ) secures the fitting element ( 3 ) to the socket ( 2 ), an extractor ( 6 ) partly housed in the outer body ( 5 ) and movable along the central axis ( 2   a ) relative to the outer body ( 5 ) and adapted to move the constraint element ( 4 ) from the tightening position to the release position, and comprising teeth ( 6   a ) placed between the constraint sectors ( 7 ) and suitable to maintain a minimum distance between said constraint sectors ( 7 ).

FIELD OF THE INVENTION

The present invention relates to a quick-coupling device in circuits for circulation of fluids under pressure, comprising a fitting element including a second channel, the socket comprising a central axis, a first channel internal to the socket, and an inlet of the first channel; the first channel being adapted to house the fitting element and being brought into fluid communication with the second channel; the socket further comprising an outer body defining at least part of the first channel and comprising an annular cavity opening on the first channel, a substantially annular constraint element at least partly housed in the annular cavity and movable within the cavity, and including a plurality of constraint sectors consisting of circular sectors of the constraint element which are adapted to be mutually moved in a radial direction and define a release position at which the constraint element is retracted into the annular cavity in such a manner as to enable movement of the fitting element relative to the socket, and a tightening position at which the constraint element tightly secures the fitting element to the socket, an extractor partly housed in the outer body and movable along the central axis relative to the outer body, and adapted to move the constraint element from the tightening position to the release position.

DESCRIPTION OF THE PRIOR ART

This quick-coupling device is a device adapted to enable the connecting and disconnecting operations on pipes belonging to lines for circulation of fluids, possibly under pressure, to be made simple, safe and immediate, without needing use of particular tools.

It is known that for accomplishment of hydraulic lines for fluids under pressure union of pipes to tanks, other pipelines or different other elements is required through means adapted to bring them into communication for fluid passage.

This means can contemplate two components, at least one of which is rigidly connected to one of the two pipes through suitable solutions such as welding or forcing operations, or pipe-clamping bands. These components are usually provided with threads adapted to mutually link them forming the above mentioned connection. However, quick couplings are presently more and more frequently preferred to the above described means, the couplings being adapted to enable two pipes to be connected and disconnected through simple and quick manual operations. These couplings usually have two base elements: a socket and a fitting element adapted to be partly inserted in the socket.

In a first example of a coupling, described for example in ISO Standard 8434-1:2007(E) it is provided that connection between the fitting element and socket will take place by a forcing operation. In particular, in the socket the presence of three elements is contemplated: a first base body provided with a thread, a nut suitable for engagement with said thread and a conical element housed between said two components, in a suitable cavity formed in the base body. When the nut is secured to the base body, the conical element is forced between said base body and the fitting element thus creating the constraint.

Another type of coupling devices consists of the so-called quick couplings. In these couplings the fitting element has a throat or overhang on the outer surface, while the socket comprises an outer casing having a cylindrical cavity adapted to house the fitting element. This cavity further has a hollow in which a plurality of constraint elements are housed which are adapted to be radially moved due to the presence of an elastic O-ring.

At the beginning, the fitting element is inserted in the socket and the constraint elements are pushed by the outer surface of the fitting element into the hollow thus compressing the elastic ring. When the throat or overhang faces the constraint elements, the elastic ring radially pushes said elements that are inserted in the throat forming a constraint between fitting element and socket.

Finally, to enable quick release of this constraint, a sliding body is provided that, when manually pushed by an operator, disengages the constraint elements from the throat or overhang enabling separation of the fitting element from the socket. The above described known art has some important drawbacks.

In fact, both types of quick couplings presently known are subject to quick deterioration.

In the first example described above, in fact, the engagement and disengagement operations are rather slow, because it is necessary to act through use of spanners and the like.

In addition, constraint by friction can become inseparable due to deposits or deterioration of the material and, therefore, it becomes impossible to replace possible faulty components. In some cases, even use of suitable tools such as spanners for example, can be insufficient to release the constraint.

In the second example, a displacement of the constraint elements can occur which can bring to an unsteadiness of the quick coupling, i.e. the incapacity for supporting high pressures.

A further problem is given by the fact that known quick couplings are not adapted to withstand high pressures.

Still another problem is represented by the fact that the two types of actuators are not interchangeable with each other, i.e. it is impossible to couple the fitting element of one with the socket of the other.

SUMMARY OF THE INVENTION

Under this situation, the technical task underlying the present invention is to conceive a quick-coupling device for pipelines and the like capable of substantially obviating the mentioned drawbacks.

Within the scope of this technical task, it is an important aim of the invention to conceive a reliable and durable quick-coupling device. In particular, it is an important aim of the invention to enable the quick-coupling device to be used with ease and to avoid deterioration of same due to use.

A further fundamental aim of the invention is to obtain a quick-coupling device adapted to withstand high pressures.

Another important aim of the invention is to provide a device that is at least partly usable with the types of couplings presently known, in particular with the coupling in accordance with ISO Standard 8434-1:2007(E).

The technical task mentioned and the aims specified are achieved by a quick-coupling device in circuits for circulation of fluids under pressure, comprising a fitting element including a second channel, the socket comprising a central axis, a first channel internal to the socket, and an inlet of the first channel; the first channel being adapted to house the fitting element and being brought into fluid communication with the second channel; the socket further comprising an outer body defining at least part of the first channel and comprising an annular cavity opening on the first channel, a substantially annular constraint element at least partly housed in the annular cavity and movable within the cavity, and including a plurality of constraint sectors consisting of circular sectors of the constraint element which are adapted to be mutually moved in a radial direction and define a release position at which the constraint element is retracted into the annular cavity in such a manner as to enable movement of the fitting element relative to the socket, and a tightening position at which the constraint element tightly secures the fitting element to the socket, an extractor comprising feet placed between the constraint sectors, adapted to maintain a minimum distance between the constraint sectors and partly housed in the outer body and movable along the central axis relative to the outer body, and adapted to move the constraint element from the tightening position to the release position.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention are hereinafter clarified by the detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, in which:

FIG. 1 shows a scale quick-coupling device according to the invention;

FIG. 2 shows an element of the quick coupling partly in section;

FIG. 3 shows a component of the element seen in FIG. 2 partly in section;

FIG. 4 is a sectional view of a second component of the element seen in FIG. 2;

FIG. 5 a is a sectional view of an assembly consisting of two other components of the element in FIG. 2;

FIG. 5 b is a top view of the assembly shown in FIG. 5 a;

FIG. 6 reproduces a further component of the element seen in FIG. 2;

FIG. 7 represents a partly sectional view of a second element of the quick-coupling device in accordance with the invention;

FIG. 8 diagrammatically shows a particular coupling partly of known type, in accordance with ISO Standard 8434-1:2007;

FIG. 9 reproduces a possible configuration of the quick-coupling device according to the invention;

FIG. 10 shows a second possible configuration of the quick-coupling device according to the invention;

FIG. 11 shows a third possible configuration of the quick-coupling device in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, the quick-coupling device for pipelines and the like in accordance with the invention has been generally identified by reference numeral 1.

It is adapted to connect, in a quick and easily separable manner, two pipes 20 or, alternatively, one pipe 20 to a device such as a compressor, a tank or other similar device.

The quick coupling 1 comprises a socket 2 having a central axis 2 a and a fitting element 3 adapted to be partly fitted in socket 2 and coupled thereto, preferably being of cylindrical shape. In particular, the fitting element 3 is connected to a pipe 20, while socket 2 is connected to a tank or the like by threading.

The socket 2 and fitting element 3 internally have a first channel 2 d and a second channel 3 b respectively, that are mutually connected for fluid passage, when the socket 2 a and fitting element 3 are fastened to each other. In more detail, the first channel 2 d is adapted to receive the fitting element 3 through an inlet 2 c. The second channel 3 b on the contrary comprises an outlet 3 e through which the fluid flows from the fitting element 3 to the socket.

The fitting element 3, shown in FIG. 7, externally has a coupling surface 3 d that is substantially cylindrical and an axis of which is substantially coincident with the central axis 2 a, when the fitting element is inserted in the socket 2. Furthermore, this coupling surface 3 d is continuous, i.e. devoid of overhangs or other similar elements except for a single discontinuity represented by a throat 3 a that is axially symmetric to, and made to a given distance from the outlet 3 e, as hereinafter better specified. It also has a counter-surface 3 c close to the outlet 3 e and substantially perpendicular to the central axis 2 a.

The socket 2 in summary comprises a constraint element 4 that can be moved in a radial direction relative to the central axis 2 a and preferably has an almost circular shape, an outer body 5 defining a first portion of channel 2 c and adapted to at least partly contain the constraint element 4, and an extractor 6 defining a second portion of channel 2 c and adapted to move relative to the outer body 5 in a direction almost parallel to the central axis 2 a.

In greater detail, the outer body 5 has an annular cavity 5 a facing cavity 2 c and adapted to at least partly house the constraint element 4. This annular cavity 5 a extends, as shown in FIG. 3, in an inclined direction 5 b relative to the central axis 2 a through an angle α in such a manner that the constraint element 4, when it deviates in a radial direction towards the central axis 2 a, simultaneously moves in the direction of the central axis 2 a towards the inlet 2 c. In particular, angle α is substantially included between 45° and 55° and, preferably, angle α is included between 48° and 52°.

Finally, the body 5 substantially has a cylindrical shape and, preferably, a suitably shaped outer surface so that it can be easily grasped by prong spanners or the like. Further, it can be advantageously provided with an outer thread adapted to carry out a connection by screwing with a tank or the like.

The constraint element 4 advantageously comprises a plurality of constraint sectors 7, preferably four in number, that are at least partly housed in the annular cavity 5 a. The constraint sectors 7 are adapted to be mutually and radially moved.

In detail, due to the particular geometry of the annular cavity 5 a, sectors 7, during their radial displacement, advantageously move along an inclined direction 5 b, i.e. they simultaneously move in a radial direction and in a direction parallel to the central axis 2 a to the inlet 2 c.

Said movement allows two different positions of the constraint element 4 to be defined: a release position (FIGS. 10 and 11) at which positioning of the constraint sectors 7 is adapted to enable movement of the fitting element 3 relative to socket 2; and a tightening position at which the constraint sectors mutually and tightly connect said two components.

In detail, in the tightening position only a portion of the constraint element 4 is inside cavity 5 a, while in the release position the constraint sectors 7 are spaced apart from each other to a greater extend and almost fully disposed within cavity 5 a. In conclusion, in moving from the release position to the tightening position, there is a reduction in the distance between the constraint sectors 7 and a consequent reduction in the diameter of the constraint element 4, respectively.

In particular, reduction in the distance between the constraint sectors 7 is obtained through a spring 8 externally surrounding the constraint element 4, as shown in FIGS. 5 a and 5 b. Said spring is disposed within a housing 7 a placed on the outer edge, i.e. the one to a greater distance from the central axis 2 a, of each constraint sector 7. In addition, spring 8 is adapted to take up almost the whole height of the housing 7 a calculated in a direction parallel to the central axis 2 a, so as to ensure correct positioning of spring 8 and avoid undesired movements of same.

In detail, spring 8 is a metal helical spring preferably made of steel and preferably a spiral spring the ends 8 a of which are rectilinear in order to avoid them being inserted between two constraint sectors 7, when the constraint element is in a release position, inhibiting return to the tightening position. In particular, the ends 8 a are tangent to the circumference defined by spring 8 in a rest position (FIG. 2).

Finally, each of the constraint sectors 7 has a projection 7 b on its face close to the central axis 2 a, as shown in FIGS. 5 a and 5 b, which projection in the tightening position enters cavity 3 a locking the fitting element 3 and socket 2 with each other while, upon movement to the release position, it comes out of said cavity 3 a enabling mutual motion between the fitting element 3 and socket 2.

The projection 7 b has an upper conical wall 7 c advantageously extending in an oblique direction 7 d, being inclined through an angle β relative to the central axis 2 a (FIG. 5 a) and adapted to allow movement of the constraint element 4 from the tightening position to the release position, when the fitting element 3 is inserted in socket 2. In particular, the fitting element 3, when inserted in socket 2, exerts pressure on the upper conical surface 7 c causing sectors 7 to enter the annular cavity 5 a and therefore allowing full introduction of the fitting element 3. In particular angle β is substantially included between 45° and 55° and, preferably, it is included between 48° and 52°.

In addition, due to the presence of a lower wall 7 g, extraction of the fitting element 3 is facilitated. In fact, the extractor 6 is adapted to press on said upper conical wall 7 c so as to move the constraint element 4 from the tightening position to the release position, thus clearing the throat 3 a and allowing the fitting element 3 to be pulled out.

In addition, projection 7 b has a lower surface 7 e almost perpendicular to the central axis 2 a, said surface being adapted to interact with the counter-surface 3 c of the throat 3 a. Due to this geometry, in the extraction direction of the fitting element 3 the lower surface 7 e abuts against the counter-surface 3 c preventing the fitting element 3 from being pulled out and tightening it in alignment with axis 2 a. This advantage is also obtained due to the cavity 5 a that, being inclined in the opposite direction relative to the extraction direction of the fitting element 3, prevents an undesired separation of the quick-coupling device 1. Furthermore, the upper surface of the cavity 5 a promotes entry of the projection 7 b into the throat 3 a when tightening occurs.

Finally, each sector 7 has a cylindrical surface if with an axis substantially coincident with axis 2 a, suitably under the lower surface 7 e and preferably also at projection 7 b.

The extractor 6 is adapted to move relative to the outer body 5 in a direction almost parallel to the central axis 2 a and is advantageously provided, at the lower base opposite to the abutment disc 6 b, with teeth 6 a (FIG. 4) adapted to be disposed between the constraint sectors 7. In particular, when the constraint element 4 moves to a tightening position, the constraint sectors 7 abut against teeth 6 a determining a minimum distance between said constraint sectors 7 and, therefore, a minimum size of the constraint element 4. Finally, the number of teeth 6 a is preferably the same as that of the constraint sectors 7, i.e. four.

In addition, the lower base of extractor 6 and the upper base of the constraint element 4 are advantageously inclined to the central axis 2 a and parallel to each other, so that movement of extractor 6 gives rise to a displacement of the constraint sectors 7 and vice versa. In greater detail, lowering of extractor 6 causes an increase in the sizes of the constraint element 4, i.e. passage of same to a release position (FIG. 1), whereas a reduction in the sizes of the constraint element 4, i.e. a return to the tightened position, causes raising of extractor 6.

In addition, the extractor 6 is partly housed within the outer body 5 and has an almost cylindrical shape. At the base external to the outer body 5 it has an abutment disc 6 b (FIG. 4) adapted to bear against the upper edge of the external body 5 when the extractor 6 is pressed against said outer body 5.

Socket 2 in addition to the above mentioned components comprises a stop ring 9 adapted to be inserted, once locking between fitting element 3 and socket 2 has been completed, between the abutment disc 6 b and the outer body 5 to prevent movement of extractor 6 relative to said outer body 5. Preferably the stop ring 9 is an open spring ring, i.e. its circumference is split and more specifically it is a Seger ring or the like.

In order to prevent extractor 6 from coming out of the outer body 5, the extractor stroke is further limited by a retainer 10 shown in Hg. 2. This retainer 10 is simultaneously housed in two grooves 10 a formed in the extractor 6 and the outer body 5 and adapted to always face each other at least partly.

Retainer 10 preferably consists of an open spring ring so as to facilitate insertion thereof into grooves 10 a. In particular, during the mounting step, it is enlarged and easily inserted in the grooves 10 a of extractor 6. Once it has been positioned, it is allowed to expand so as to adhere to said groove 10 a and, finally, extractor 6 is forcibly inserted into the outer body 2.

Socket 2 further comprises an O-ring 11 or other similar means adapted to ensure the sealing action of the fluid coupling 1. The O-ring 11 is advantageously at least partly housed in a hollow 5 c (FIG. 3) conveniently formed in the outer body 5 under cavity 5 a and, in order to avoid dangerous displacements of the O-ring 11, a sealing component 11 a, a ring for example, can be disposed within the hollow 5 c, so as to lock the O-ring 11 in the hollow 5 c.

Shown in FIG. 8 is a second possible configuration of the ogive-shaped coupling device according to ISO Standard 8434-1:2007, which is adapted to bring into fluid connection two pipes 20 or one pipe 20 to a device, such as a tank.

In this example the coupling device comprises a fitting element 3 and a socket 102 having a central axis 102 a and including a first channel 102 d adapted to house the fitting element 3.

Socket 102, as shown in FIG. 8, has a locking element 104 adapted to secure the fitting element 3 to the socket 102 by tightening, a base body 105 provided with a cavity 105 a adapted to at least partly contain the locking element 104, and a closing element 106 adapted to be secured to the base body 101, preferably by threading, carrying out said tightening of the locking element 104.

In this preferred embodiment, the closing element 106 is adapted to be moved along the central axis 102 a and to be rigidly secured to the base body 105 by a threaded coupling, while the locking element 104 has an almost cylindrical shape characterised by a frustoconical end adapted to be inserted in cavity 105 a.

In particular, after the fitting element 3 has been inserted into the socket 102, the closing element 106, being secured to the base body 105, presses the locking element 104 within the cavity 105 a, which locking element is therefore forced between the fitting element 3 and socket 102 thus carrying out tightening of the fitting element 3 to socket 102.

The socket 102 preferably has sizes in accordance with ISO Standard 8434-1:2007 or subsequent modifications to said ISO Standard.

The fitting element 3, shown in FIG. 7, is the one previously described and the given distance of throat 3 a is greater than the distance between the cavity 105 a and outlet 3 e when the fitting element 3 is secured to the socket 102, so that it does not interfere with said tightening action.

Finally, as in the preceding preferred embodiment, throat 3 a has a counter-surface 3 c, i.e. the surface of throat 3 a close to the outlet 3 e, that is preferably substantially perpendicular to the central axis 102 a.

Operation of the quick-coupling device for pipelines and the like described above as regards structure is the following.

Once pipes 20 have been connected to socket 2 and to the fitting element 3, the fitting element 3 is inserted into socket 2 so that said components are secured to each other.

The fitting element 3 passes through the extractor 6 and abuts against the projections 7 b of the constraint sectors 7. Then the fitting element 3 starts pressing on said projections 7 b causing passage from the tightening position to the release position of the constraint element 4.

In particular, the constraint sectors 7 are moved apart from each other, i.e. the constraint element increases its diameter and the constraint sectors 7 are almost fully housed within cavity 5 a (FIG. 10) thus enabling the fitting element 3 to complete its fitting. In particular, the fitting element 3 continuing its travel comes into contact with the O-ring 11 deforming it and carrying out a fluid-tight connection.

When the fitting element 3 is inserted, the throat 3 a faces the constraint sectors 7 that, being pressed by spring 8, urge the projections 7 b into said throat 3 a securing the fitting element 3 to the socket 2 and bringing the constraint element 4 back to its tightening position, as shown in FIG. 4.

In addition, due to their displacement, the constraint sectors 7 abut the teeth 6 a bringing the constraint element 4 to sizes close to the minimum ones, but not strictly coincident with said minimum sizes. Consequently, the constraint element 4 axially compresses the fitting element 3 centring it on axis 2 a, in particular by means of the cylindrical surface 7 f.

In addition, before locking, the stop ring 9 is preferably introduced between the abutment disc 6 b and the outer body 5 inhibiting any motion of the extractor 6, so as to avoid an undesirable disengagement of the quick-coupling device 1.

When the quick-coupling device 1 is wished to be disengaged, i.e. the fitting element 3 is wished to be separated from socket 2, the stop ring 9 is removed from its housing and the extractor is lowered bringing the abutment disc 6 b almost in contact with the outer body 5.

This movement of extractor 6 causes passage of the constraint element 4 from the tightening position to the release position, i.e. projections 7 b of the constraint sectors 7 come out of throat 3 a enabling the fitting element 3 to be pulled out of socket 2.

Once the fitting element 3 has been pulled out, the constraint element 4 due to spring 8 goes back to the tightening position with the constraint sectors 7 being adjacent to teeth 6 a, as shown in FIG. 11.

The invention enables important advantages to be achieved.

A first advantage of the quick-coupling device 1 is represented by the high reliability and duration.

In fact, due to the presence of teeth 6 a, the constraint sectors 7 going back to the tightening position are not submitted to dangerous mutual displacements and their mutual distance is almost unchanged and therefore the tightening quality between fitting element 3 and socket 2 is not lowered.

Another advantage is represented by the quick-coupling device ability that is ensured by the particular geometry of the lower surface 7 e and the counter-wall 3 c. The quick-coupling device 1 is therefore able to withstand pressures up to 350 bars.

Still another advantage is provided by the metal spring 8 adapted to have a longer duration and greater spring force, also ensured by the number and shape of sectors 7.

A further important advantage is represented by the possibility of using the fitting element 3 also with ogive-shaped coupling devices of the type ISO Standard 8434-1:2007 presently known. In fact, the particular height where the throat 3 a is formed, does not prevent the known quick-coupling devices as above described to be connected and fastened.

The invention is susceptible of variations falling within the inventive idea.

All of the details can be replaced by equivalent elements and the materials, shapes and sizes can be of any nature and magnitude. 

1. A socket (2) for a quick-coupling device (1) in circuits for circulation of fluids under pressure, said quick-coupling device (1) comprising a fitting element (3) including a second channel (3 b), said socket comprising a central axis (2 a), a first channel (2 d) internal to said socket (2), and an inlet (2 c) of said first channel (2 d); said first channel (2 d) being adapted to house said fitting element (3) and being brought into fluid communication with said second channel (3 b); said socket (2) comprising an outer body (5) defining at least part of said first channel (2 d) and comprising an annular cavity (5 a) opening on said first channel (2 d), a substantially annular constraint element (4) at least partly housed in said annular cavity (5 a) and movable within said cavity, and including a plurality of constraint sectors (7) consisting of circular sectors of said constraint element (4) which are adapted to be mutually moved in a radial direction and define a release position at which said constraint element (4) is retracted into said annular cavity (5 a) in such a manner as to enable movement of said fitting element (3) relative to said socket (2), and a tightening position at which said constraint element (4) tightly secures said fitting element (3) to said socket (2), an extractor (6) comprising feet (6 a) placed between said constraint sectors (7), adapted to maintain a minimum distance between said constraint sectors (7) and partly housed in said outer body (5) and movable along said central axis (2 a) relative to said outer body (5), and adapted to move said constraint element (4) from said tightening position to said release position.
 2. A socket (2) as claimed in claim 1, comprising a spring (8) adapted to dispose said constraint element (4) in said release position in the absence of counter-forces.
 3. A socket (2) as claimed in claim 2, wherein said spring (8) is a helical metal spring and has rectilinear ends (8 a).
 4. A socket (2) as claimed in claim 3, wherein each of said constraint sectors (7) has a housing (7 a) opening on said outer body (5) and adapted to house said spring (8) at least partly.
 5. A socket (2) as claimed in claim 1, wherein said annular cavity (5 a) extends in an inclined direction (5 b) relative to said central axis (2 a) in such a manner that, when said constraint sectors (7) move in a radial direction towards said central axis (2 a), said constraint sectors (7) move simultaneously in the direction of said central axis (2 a) towards said inlet (2 c).
 6. A socket (2) as claimed in claim 1, wherein said constraint element (4), when said socket (2) houses said fitting element (3), is adapted to align said fitting element to said central axis (2 a).
 7. A socket (2) as claimed in claim 1, wherein said extractor (6) has an abutment disc (6 a) adapted to abut on said outer body (5), and wherein said socket (2) comprises a stop ring (9) adapted to be introduced between said abutment disc (6 b) and said outer body (5) thereby inhibiting the motion of said extractor (6) relative to said outer body (5).
 8. A socket (2) as claimed in claim 1, wherein said constraint sectors (7) comprise a projection (7 b) adapted to secure said fitting element (3) into said socket (2), when said constraint element (4) is in said tightening position.
 9. A socket (2) as claimed in claim 8, wherein said projection (7 b) comprises an upper conical wall (7 c) extending in an oblique direction (7 d) relative to said central axis (2 a) and adapted to allow movement of said constraint element (4) from said tightening position to said release position, when said fitting element (3) is inserted in said socket (2).
 10. A socket (2) as claimed in claim 9, wherein said extractor (6) is adapted to exert pressure on said upper conical wall (7 c) in such a manner as to move said constraint element (4) from said tightening position to said release position.
 11. A socket (2) as claimed in claim 8, wherein said projection (7 b) has a lower surface (7 e) that is substantially perpendicular to said central axis (2 a).
 12. A quick-coupling device (1) for circuits for circulation of fluids under pressure comprising a socket (2) as claimed in claim 11, and a fitting element (3) and wherein said fitting element (3) has a throat (3 a) adapted to receive said projection (7 b).
 13. A quick-coupling device (1) as claimed in claim 12, wherein said throat (3 a) has a counter-surface (3 c) which is substantially perpendicular to said central axis (2 a) and is adapted to interfere with said projection (7 b).
 14. A quick-coupling device (1) for circuits for circulation of fluids under pressure, said quick-coupling device (1) further comprising a socket (102) including a first channel (102 d) adapted to house said fitting element (3); said fitting element (3) comprising a second channel (3 b) and an outlet (3 e), said fitting element (3) being further adapted to be brought into fluid communication with said first channel (102 d) when said socket (102) houses said fitting element (3); said socket (102) including a locking element (104) adapted to connect said fitting element (3) to said socket (102) by hermetic tightening, a base body (105) provided with a cavity (105 a) adapted to at least partly contain said locking element (104), a closing element (106) adapted to be secured to said base body (105) carrying out said hermetic tightening of said locking element (104), said socket (102) being also of sizes in accordance with the ISO Standard 8434-1:2007 or subsequent modifications, said fitting element (3) having externally a substantially continuous coupling surface (3 d) exclusively including a throat (3 a) formed to a given distance from said outlet (3 e), said given distance being greater than the distance between said cavity (105 a) and said outlet (3 e) when said fitting element (3) being firmly connected to said socket (102) in such a manner as not to interfere with said hermetic tightening.
 15. A fitting element (3) as claimed in claim 14, wherein said throat (3 a) has a counter-surface (3 c) substantially perpendicular to said central axis (102 a). 